MXR MC403 CAE Power System? major ground loop issues

twenty4_7spy · Jun 26, 2011

See it at:

http://proguitarshop.com/store/acce...s-c-603_117/mxr-mc403-cae-power-system-p-1767

I am running into ground loop issues big-time. I am running the following off of a Furman SPB-8 and two 1-spots (I am suspicious of these, I have heard things about them) powering single boxes, all other pedals are either powered off the SPB-8 9v supplies or wall-warts into the SPB-8:

guitar
Visual Volume
Whammy
Vox Big Bad Wah
Fulltone Deja 2 (the older one, powered by 110v)
MXR Script Phase 90 (powered by 1-spot)
MXR EVH Flanger
G-Lab LMS-1 (powered by 1-spot)

into three Marshall-type 100W half stacks

79 JMP KS 100W (THANKS J. B.)
Marsha 100W that started as a Bray custom build
100W 12000-series clone, manufacturer unknown

The LMS-1 has ground lifts and they seem to improve things just a little, and this is with guitar volume off, just listening to the 60hz buzz. The KS JMP picks it up the worst (HBE input), and the biggest source seems to be the 12000 series clone. I am wondering if I go with unified pedal power and filtered AC like this:

http://www.monstercable.com/productdisplay.asp?pin=2140

will there be silence? How do the big boys get huge multi-amp systems hum free? Any ideas/comments are welcome, this is driving me crazy!!!!

Thanks,

Matt

Giga · Jun 26, 2011

Yeah, that can be quite a challange...

Start with: guitar -> LMS1 -> 1 amp, then add amp 2, then amp 3. Then start adding the pedals with their respective powersupplies one by one and observe where it goes wrong.

Good luck !

Giga

steve_k · Jun 26, 2011

You probably have two things against you. One being some pedal issues and the One Spot and the other being the 3 amps from the G-Lab. But, you should be able to systematically nail it down. Start with the pedal board and all that stuff you got going with it into just one amp, to at least get that part of it ruled out or isolated. I am not familiar with that G-lab product, but you might bypass all the pedals and just try the switcher with the 3 amps and see how that goes. You should be able to nail it from there. You need good quality ISO out of your switcher. The One Spot is not really the way to go up front either.

Steve